package com.lagou.sqlSesssion;

import com.lagou.config.BoundSql;
import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;
import com.lagou.utils.GenericTokenParser;
import com.lagou.utils.ParameterMapping;
import com.lagou.utils.ParameterMappingTokenHandler;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

/**
 * TODO
 *
 * @author harmony
 * @description 执行器实例
 * @date 2020/12/9 20:55
 */
public class SimpleExecutor implements Executor{
    @Override
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object... params) throws SQLException, ClassNotFoundException, NoSuchFieldException, IllegalAccessException, InvocationTargetException, InstantiationException, IntrospectionException {

        //1.加载驱动
        Connection connection = configuration.getDataSource().getConnection();

        //2.获取sql
        String sql = mappedStatement.getSql();

        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理器
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        //4.设置参数

        //获取参数全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass = getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(content);
            //暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);

            preparedStatement.setObject(i+1,o);
        }

        //5.执行sql
        ResultSet resultSet = preparedStatement.executeQuery();

        //6.封装返回结果集
        String resultType = mappedStatement.getResultType();
        Class<?> resultTypeClass = getClassType(resultType);

        ArrayList<Object> objects = new ArrayList<>();

        while (resultSet.next()){
            Object o = resultTypeClass.newInstance();
            //元数据
            ResultSetMetaData metaData = resultSet.getMetaData();
            for (int i = 1; i <= metaData.getColumnCount(); i++) {
                String columnName = metaData.getColumnName(i);
                Object value = resultSet.getObject(columnName);

                //使用反射或者内省，根据数据库表和实体的对应关系，完成封装
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, resultTypeClass);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o, value);
            }
            objects.add(o);
        }


        return (List<E>) objects;
    }

    @Override
    public Integer update(Configuration configuration, MappedStatement mappedStatement, Object[] params) throws Exception {
        //1.加载驱动
        Connection connection = configuration.getDataSource().getConnection();

        //2.获取sql
        String sql = mappedStatement.getSql();

        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理器
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        //4.设置参数

        //获取参数全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass = getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(content);
            //暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);

            preparedStatement.setObject(i+1,o);
        }

        //5.执行sql
        int i = preparedStatement.executeUpdate();
        return i;
    }

    @Override
    public Integer delete(Configuration configuration, MappedStatement mappedStatement, Object[] params) throws Exception{
        //1.加载驱动
        Connection connection = configuration.getDataSource().getConnection();

        //2.获取sql
        String sql = mappedStatement.getSql();

        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理器
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        //4.设置参数

        //获取参数全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass = getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();
            //因为参数不是对象不需要反射获取
            preparedStatement.setObject(i+1,params[0]);
        }

        //5.执行sql
        int i = preparedStatement.executeUpdate();
        return i;
    }

    @Override
    public Integer insert(Configuration configuration, MappedStatement mappedStatement, Object[] params) throws Exception{
        //1.加载驱动
        Connection connection = configuration.getDataSource().getConnection();

        //2.获取sql
        String sql = mappedStatement.getSql();

        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理器
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        //4.设置参数

        //获取参数全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass = getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(content);
            //暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);

            preparedStatement.setObject(i+1,o);
        }

        //5.执行sql
        int i = preparedStatement.executeUpdate();
        return i;
    }

    private Class<?> getClassType(String parameterType) throws ClassNotFoundException {
        if(parameterType != null){
            Class<?> aClass = Class.forName(parameterType);
            return aClass;
        }
        return null;
    }

    private BoundSql getBoundSql(String sql) {
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParser genericTokenParser = new GenericTokenParser("#{", "}", parameterMappingTokenHandler);
        String sqlText = genericTokenParser.parse(sql);
        List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();
        return new BoundSql(sqlText,parameterMappings);
    }
}
